import matplotlib.pyplot as plt  
import pandas as pd  
import requests  
import io  
import numpy as np  
 
url = 'https://blog.topspeedsnail.com/wp-content/uploads/2016/12/铁路客运量.csv' 
ass_data = requests.get(url).content  
 
df = pd.read_csv(io.StringIO(ass_data.decode('utf-8')))  # python2使用StringIO.StringIO  
 
data = np.array(df['铁路客运量_当期值(万人)'])  
# normalize  
normalized_data = (data - np.mean(data)) / np.std(data)  
 
plt.figure()  
plt.plot(data)  
plt.show()